In today's electronic age and particularly as a result of advances in digital technologies, electrical malfunctions resulting from electromagnetic radiation such as radio frequency interference (RFI) have been proliferating. Recently, ever-increasing numbers of cordless and cellular phone users have compounded the problem. As a result, interference with clear communication and the shielding of communication equipment from stray radio frequency signals has become a primary concern.
As a result, many efforts have been made in recent years to mitigate RFI. Examples of these efforts are found in U.S. Pat. Nos. 5,371,404 to Juskey et al. and 5,338,617 to Workinger et al. The Juskey et al. patent discloses a semiconductor device package incorporating a thermally and electrically conductive plastic material containing metal particles that is transfer molded to encapsulate the semiconductor device. The conductive plastic material is electrically connected to the circuit ground to shield the semiconductor device from radio frequency energy and is mechanically attached to the semiconductor device to dissipate heat. Fins may be molded into the plastic conductive material for heat dissipation. The Workinger et al. patent discloses a radio frequency shield that underlies the conductors of a radio frequency assembly but does not enclose them. The shield is formed from metal powder particles in a plastic resin.
While the shields disclosed in the Juskey et al. and Workinger et al. patents are useful for their intended purpose, they are not without their shortcomings. Specifically, the Juskey et al. device package requires transfer molding so that the semiconductor device is encapsulated in the thermally and electrically conductive plastic material. This transfer molding requires the application of heat to the semiconductor device. This limits the selection of shielding materials to relatively low temperature thermoplastic materials since higher temperature thermoplastic materials risk potential damage to the semiconductor device through the application of high temperatures. The Workinger et al. shield does not enclose the conductors or component to be shielded and as such fails to provide sufficient shielding for many applications.
Thus, a need is identified for an improved means of mitigating electromagnetic radiation including radio frequency interference overcoming the above-identified disadvantages and limitations of the prior art.